Mechanical pencils are well known. For example, such pencils typically include a barrel, a lead feeding mechanism disposed in the barrel and a lead holder disposed in the tip of the lead feeding mechanism to hold the lead penetrating therethrough and an operating part to feed the lead.
For example, a mechanical pencil including a barrel, a lead feeding mechanism disposed in the barrel to tighten and feed a piece of lead and a lead holder disposed between the lead feeding mechanism and a tip end of the barrel is disclosed in a U.S. Pat. No. 6,908,246 of Kageyama et al. As disclosed therein, the lead holder includes a through hole through which the lead penetrates, holding portions for holding the lead, and a contact portion for contacting an inner peripheral face of the barrel. The holding portion includes a first holding portion at a first position of the lead holder and a second holding portion at a rear portion of the lead holder. When a length of lead becomes shorter than a distance between the lead feeding mechanism and the end of the barrel, the first holding part holds the short lead and the second holding portion holds a next piece of lead.
Mechanical pencils of the above type have been used and serve the needs of an average individual. However, such pencils do not adequately serve the needs of some artists. The problem is that artists frequently use various types of pencils in making sketches and frequently include pencils of different hardness in their writing supplies and/or writing cases. However, there are times when an artist does not have his or her supplies at hand and yet would like to have a pencil with leads of different hardness. For this reason, it is believed that there may be a demand for an improved writing instrument in accordance with the present invention. There should be a demand because such pencils include a single piece of lead and at the same time provide the characteristics of a multi-hardness pencil.
Further, the writing instrument in accordance with the present invention includes replaceable leads, has a minimum number of parts, and is durable, easy to use and easy to select a pre-selected force on a lead. Such instruments can also be manufactured and sold at a relatively low cost and provide an artist as well as a relatively untrained or new artist an ability to select different effects from a single piece of lead of a single hardness.